Caytoniales General Characteristics

What are Caytoniales?

Ø  Caytoniales were a small group of extinct Gymnospermic plants.

Ø  First described by Hamshaw Thomas in 1925 from the late Triassic period.

Ø  Caytonia is a berry-like cupules with numerous small seeds.

Examples of Caytoniales

Ø  Leaves: Sagenopteris

Ø  Microsporophylls: Caytonanthus

Ø  Megasporophylls: Caytonia and Gristhorpia

General Characteristics of Caytoniales

Ø  Caytoniales were small branched trees or shrubs.

Leaves (Sagenopteris)

Ø  Leaves petiolate

Ø  Petiole slender with 3 to 6 terminal leaflets.

Ø  Leaflets arrangement was palmate in pairs.

Ø  Each leaflet with distinct midrib.

Ø  Leaf margin smooth with an acute apex.

Ø  Venation similar to Glossopteris

Learn more: General Characteristics of Glossopteridales

Ø  Upper and lower epidermis with thick cuticle.

Ø  Stomata were abundant on the lower surface of the leaf.

Ø  Stomatal development haplocheilic.

Ø  Mesophyll differentiated into palisade and transfusion tissue.

Ø  Leaflets fall by the formation of abscission layers (it is an Angiospermic character).

Ø  Caytoniales had fertile branches with seed-bearing cupules.

Ø  Ovules were located inside the fleshy cupules with tough outer cuticle.

Ø  Outer layers of the cupules were fleshy and fruit-like.

Ø  Individual ovules had an apical tube like structure called micropylar canal.

Ø  The micropylar canal facilitates the passage of pollen into the pollen chamber.

Ø  Mature ovule resembles a blueberry fruit.

Ø  The extra protection of seeds in Caytoniales indicates they were predecessors of Angiosperms.

Microsporophyll

Ø  Example: Caytonanthus

Ø  Microsporophyll consists of dorsi-vental and pinnate rachis.

Ø  Each rachis bears pinnae on either side.

Ø  Each pinnae branches irregularly.

Ø  The ultimate branches of pinnae bear the synangia.

Ø  Each branch bears two sporangia terminally.

Ø  Each sporangium was with four pollen sacks.

Ø  Pollen grains were produced in the pollen sacs in groups of four.

Ø  Pollen grains were small, shape similar to that of pine trees.

Ø  Pollen grains winged.

Ø  Pollination is achieved through the wind.

Megasporophyll

Ø  Example: Caytonia and Gristhorpia

Ø  Megasporophylls were also pinnate.

Ø  It consists of a dorsi-ventral rachis with a number of outgrowths.

Ø  Outgrowths were staked and with swollen tips (like berries).

Ø  These outgrowths were called the “Fruits”.

Ø  The swollen portion of the rachis contains many ovules internally.

Ø  After maturation, the ‘fruits’ also fall by abscission (like leaves).

Ø  Fruits surface smooth.

Ø  Sees were pendulous, orthotropous, oval or flattened.

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@. Glossopteridales – General Characteristics

@. Pteridospermales – General Characteristics

@. Gymnosperms – General Characteristics

@. Gymnosperms – Classification